Outbound link domain dimension
The outbound link domain is the external host a visitor clicked toward — for example partner.com when leaving your site. GA4 captures it as link_domain on click events when enhanced measurement's outbound clicks are on. This page explains derivation, the difference from referrer, and why some outbound clicks go uncounted.
What this means
An outbound link is any link from your site to a different domain. GA4's enhanced measurement fires a click event with a link_domain (and link_url) parameter when a visitor clicks one, letting you analyse exits by destination host.
The domain dimension aggregates those clicks: instead of hundreds of distinct URLs you see traffic grouped by where it went — affiliate.com, youtube.com, a partner site — which is the right altitude for referral analysis.
- Outbound link = link to a different domain
- GA4 captures link_domain on click events
- Groups exits by destination host
Limits and the referrer contrast
Outbound-click measurement depends on a JavaScript listener, so clicks it cannot intercept — middle-click new tabs in some setups, JavaScript-driven navigations, or links added after the listener bound — may be undercounted. It is a best-effort signal, not a ledger.
It is also the mirror image of the referrer dimension. Referrer tells you the domain a visitor came from; outbound link domain tells you the domain they went to. The first is inbound attribution; the second is exit behaviour. Reading them together maps both ends of a visit.
- Relies on a JS listener; some clicks go uncounted
- Referrer = where they came from; this = where they went
- Best-effort exit signal, not a complete ledger
How it appears in analytics and logs
An outbound link domain value means a visitor clicked a link to that external host. Missing outbound data usually means enhanced measurement is off or the clicks happen in ways the listener cannot catch.
Diagnostic use case
See which external destinations your visitors leave for — partners, affiliates, social profiles — to measure referral value and exit intent.
What WebmasterID can help detect
WebmasterID records outbound clicks as first-party events, so you can attribute exits to destination domains without third-party tracking on the linked sites.
Common mistakes
- Assuming every outbound click is captured.
- Confusing outbound link domain with the inbound referrer.
- Forgetting outbound clicks need enhanced measurement enabled.
Privacy and accuracy notes
The destination domain describes where a click went, not who clicked. It is link metadata and carries no personal identifier on its own.
Related pages
- Link URL dimension: where outbound clicks go
Link URL is the dimension that records the destination of a clicked link. In GA4 it is populated by the click event from enhanced measurement, which fires on outbound links and carries link_url, link_domain, and link_text. It answers 'where did people leave to?', but its automatic scope is limited to links leaving your domain — internal and same-domain clicks need separate handling.
- Page referrer dimension
Page referrer is the dimension that records the full URL a visitor came from before the current page — captured by GA4 as the page_referrer parameter on page_view. It is event-scoped and granular: it shows the immediate previous page, including internal navigations within your own site. That makes it different from the session-level source/medium, which describes how the whole visit began rather than each hop.
- The click event and outbound clicks
A click event records that a visitor activated a link or element. The most common analytics use is the outbound click — a click on a link leaving your domain — which a normal page_view can never capture because the destination is another site. This page covers what to record on a click, how outbound detection works, and which properties stay privacy-safe.
- CTA tracking
Record outbound clicks as first-party events.
Sources and verification notes
- Google Analytics Help — [GA4] Enhanced measurement (outbound clicks)Documents link_domain / link_url on outbound click events.
- MDN — HTMLAnchorElement: hostnameHow the destination host is read from a link.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.